Air cooled piston



April 1938. G. A. SPELTS 2,115,291

AIR COOLED PISTON Filed Dec. 7, 1937 Patented Apr. 26,1938

UNITED STATES AIR COOLED' PISTON George Allen Spelts, Los Angeles, Calif., assignor I of thirty percent to L. J. Styskal and seven percent to W. Fred Arndt,

County, Calif.

both of Los Angeles Application December 7, 1937, Serial No. 178,546

Claims. (01. 123-176) My invention relates to internal combustion engines in general, more especially to two stroke cycle, and particularly to such engines in which it is desirable to cool the pistons thereof.

The desirability of cooling the piston, and especially the piston head, in internal combustion engines has been recognized for a long time. In stationary engines, it is not uncommon at night to see the head operating at a dull red color. Often the head becomes so heated as to cause its freezing into the cylinder walls, with consequent damage to the engine. piston rods have been found pushed through the head.

Many attempts have been made to eliminate or mitigate the heating of a piston to a harmful temperature. The most common method is to cool the head with oil forced under pressure to the inside of the head through holes drilled in the connecting rod. Other methods have been used.

All previous attempts at satisfactorily cooling the piston of an internal combustion engine have resulted in undesirable complications. These complications impaired the reliability of the engine and also increased the manufacturing cost out of proportion to the increased utility of the engine,

It is therefore an object of my invention to provide a cooling system for a piston of an internal combustion engine which is simple, reliable, and eflicient.

It is a further object of my invention to provide a piston capable of being cooled efficiently.

It is another object of my invention to provide an internal combustion engine adapted to operate with a cooled piston.

Briefly, I accomplish these objects by providing a vigorous and positive stream of air or other fluid flowing through the piston and contacting the head. This stream is obtained without any complicating mechanism, but is provided by the action of the exhaust gases which travel at a relatively high speed.

My invention possesses many other advantages and has other objects which may be made more easily apparent from a consideration of certain embodiments of my invention. For this purpose I have shown several forms in the drawing accompanying and forming'part of the present specification. these forms in detail, which illustrate the general principles of my invention; but it is to be understood thatthis description is not to be taken in a limiting sense, since the scope of my invention is best defined by the subjoined claims.

In the drawing:

Figure 1 represents a longitudinal cross section of the cylinder and piston of an internal Sometimes I shall now proceed to describe combustion engine utilizing my system for cooling a piston efliciently.

Figure 2 represents aplan view of' the outside of my piston. A

Figure 3 represents across section of my piston taken along the plane 3--3 of Figure 1.

Referring now particularly to Figure 1, I show a cylinder to having a head H. snugly and slidably fitted into the cylinder wall is in the customary manner. For convenience and clarity I have not shown immaterial details such as piston rings or port bridges. These must be understood to be present in any well known manner.

The cylinder is provided with a jacket M defining, together with the cylinder Walls l3, Water spaces l5. l5 and may have an inlet valve Hi.

My piston l2 has a head or firing end l8, an enclosing plate |9, and side walls 29. The side walls have an opening or series of openings 2i therein (see Figure 2) and also an opening or series of openings 22. These openings are preferably, though not at all necessarily,'-formed on opposite sides of the piston.

Opening 2| registers with an opening or series of openings 23 in the cylinder Ill, saidopenings extending from the inside of cylinder wall l3 through the cylinder to the outside of jacket l4. Similarly, openings 22 in the piston register with openings 24 in the cylinder.

The cylinder is also provided with an exhaust port 25 as customarily utilized in two stroke cycle engines. An exhaust pipe25 extends from the exhaust port a short distance from the cylinder. A larger pipe or stack 26 surrounds pipe 25 and has a lower portion enlarged to completely cover opening 23, as shown clearly in Figure 1. The stack 26 may extend a sufiicient distance to convey the exhaust gases from the engine. The stack often extends through the roof or a Wall of the building in which the engine may be located.

Figure 1 shows my piston at the time of exhausting the burned gases. These gases escape with considerable velocity through exhaust port 25 and pipe 25. Upon reaching the end of pipe 25 these gases expand and mingle with the gases or air present in stack 26 and force the mixture outwardly in the general direction of the arrows l.

Another way of explaining the entraining action of the exhaust gases is by means of well known laws of physics. The exhaust gases traveling at high velocity are at a relatively low pressure. The air in stack 26 traveling at a slower speed is at a higher pressure. This air will naturally rush in the direction of the arrows to compensate for the partial vacuum induced by the exhaust gases.

A piston [2 is The head H also has Water spaces No matterhow the action is "explained, the important fact remains that air is sucked through openings 24, 22, into the piston l2 and out'through openings, 2| and 23 to stack 26. The

amount of air rushed through piston I1 is; con- 7 siderable and cools said piston effectively.

" the entire inside diameter of the piston, while i 22 are in register at all times.

To concentrate the cooling, effect on thepiston head, any means such as a baffle 21 may be used. All battles are preferably, but not necessarily, formed'to completely divide the'inside' of the piston into two parts connected'by 'a relatively thin passage of awidth equal to the inside diameter of the piston; This forces" all the air. into sweeping contact with the-piston head and cools the head efiiciently.

Figure 3 showsbafile 21 as extending across Figure'Z shows 3 sets of 2 openings forming opening or passage 21 in piston I2., It must be understood that the number and form of these openings may be varied to .suit different conditions without departing from the essence. of my invention As the piston moves rightwardly, exhausting ends, but the gases now in stack 26 still have considerable velocity'and are capable of sucking more air through the piston. For this reason 'Ihave' shown passages 2'! and 22. of such dimensions as to allow a continuous stream of cooling medium to pass through the piston. As passages 2i and J3. become outof register, passages 2| and ex- Passages 24 and However, if less cooling is required the passages maybe designed haustport 25 begin to register.

' topermit air to flow through the piston for a shorter period of time, or the size of the passage may bedecreased. In the case of a four stroke cycle engine, exhaust port 25 is not present and passages -2l may then be enlarged as are passages 22 to provide a-continuous register with passages 23.' I

'While I have shown the application of my invention to a two stroke cycle engine, it is now obvious how to apply my invention to a four stroke cycle engine by connecting pipe 25 to the exhaust manifold. 7 1

I My invention is equally applicable to Diesel engines, or to engines using vaporized fuel, pow

dered fuel, or gaseous fuel. 7 7 Having now fully described my invention in terms easily understood by: those skilled in the I claim:

1. In a two-cycle internal combustion engine, the combination with a cylinder having inlet and outletpassages in its side walls, a hollow closedpiston with inlet and outlet passages in its side walls for corresponding registration with the cylinder passages whereby 'to definea free air path through the cylinder walls and interior of said piston, the piston 'outlet passages and exhaust port being ofsuch proportions as to register during part of the piston travel with the exhaustport of the engine, and means 'for creating a flow of cooling air through the free air path,

said means utilizing a suction created by the exhaust gases.

2. In a two cycle internal combustion engine, the combinations of a cylinder having inlet and outlet passages inits side walls, the outlet passages being adjacent the exhaust port of the engine, a hollow closed piston having inlet and outlet passages in its side walls for corresponding registration with the cylinder passages whereby to define a free air path through the cylinder walls and interior of the piston during part of the piston travel, the piston outlet passages being so proportioned as to register with thefexhaust port during the remainder of its travel.

3. The combination defined in claim 2, and means for utilizing a suction created by the exfree air path. 7

il The combination, defined the exhaust port and cylinder outlet passages are at least'partially aligned longitudinally, whereby the piston outlet passages'register at least partly in claim 2,111 which 1 haust gases for creating an air. flow through the with the exhaust port and the cylinder outlet passages during part of the piston travel.

the combination comprising a'cylinder' having air inlet and outlet passages in its side walls, a'

trunk type piston having a fixed rod in one end wall, and having air inlet and outlet passages in its side walls for corresponding registration with the cylinder passageswhereby to define a terior of said piston, and means'utilizinga suction created by the exhaust gasesfor causing an air register during part of the piston travel;

6. The combination defined in claimf5, in which the cylinder outlet passages and the'ex haust port are at least partially longitudinally aligned, whereby the piston outlet passages register during part of the piston travel with both the exhaust port and the cylinder outlet passages.

7. The combination defined in claim 5, in

which the cylinder outlet passages and theexhaust port are at least partiallylongitudinally aligned, whereby the piston outlet passages regisg ter with the exhaust port during part of the piston travel, and register with the, cylinder outlet passages during the remainder of the piston travel. i

8. In a two-cycle internal combustion engine,

' free air path through the cylinder, walls, and in- 1 how through the air path, the exhaustport and t the piston outlet passages being proportioned to;

the combination comprising a cylinder having air inlet passages in its side walls, and'a hollow closed piston having air inlet passages for: registration with the cylinder inlet passages, and having outlet passages for registration with the exhaust port during part of the piston travel, during which part of the piston travel a suction created by the exhaust gases causes an air flow through the cylinder and piston interior.

9. In a two-cycle internal combustion engine,

the combination with'a cylinder having inlet and a two outlet passages in its side walls, a hollow closed piston with inlet and outlet passagesin its side walls for corresponding registration with the cylinder passages, the piston outlet passage being proportioned to register with the first ex-' haust passage in the cylinder during part of the piston travel, exhaust means for drawing air through the piston via the cylinder outlet pas sages, the piston inlet passages registering at all 15 -5. In a two cycle internal combustion engine, 

